This invention relates generally to a copying machine and more specifically to copy sheet transport methods and apparatus employed in xerographic copy equipment.
Packaging of the elements making up present day copy equipment is significant to its success in the marketplace. Compactness has meaningful significance to certain users because of economy of space as well as esthetics and other human factor considerations. The simplicity of machine construction and arrangement of course bears significantly upon such factors as maintanence and reliability.
Both compactness and simplicity have been achieved in many present day commercial copiers. These desired features are attained by exerting design pressures on the layout of the optical path and the copy sheet transport mechanisms. Previously known machine configurations have adhered to a complete separation of the optical path (projecting light images from a document to a photoresponsive member) and the copy sheet path (starting at an input tray and proceeding to the photoresponsive member where it receives a visible or toned image and then on to an output location).
A major technology for copying is, of course, xerography and it is the transfer xerography portion of the technology as distinguished from the electrofax portion that is of interest here. Transfer xerography is so named because copies of a document are made on ordinary paper. A latent image of the document is first created on a photoreceptor by exposing it to a light image of the document via an appropriate optical path. This latent image is made visible by depositing microscopic marking or toner particles on the latent image. This toned image of toner is thereafter transferred to a plain piece of paper and permanently fixed to the paper, typically by heating the toner which includes a thermoplastic component. In contrast, electrofax machines employ a copy sheet that has a photoreceptor coating. The latent image is formed, toned and fused directly on the copy sheet. This generally explains the comparatively compact and simplistic construction of electrofax copiers relative to transfer xerographic machines.
It follows that an important object of the instant invention is the improvement of transfer copying methods and apparatus.
Also, an object of the invention is to enable a copy sheet to intersect the optical path of a copying machine without effectively hindering the copying operation of the machine.
Another object intended by this invention is the development of copy sheet transport methods and apparatus that permit the movement of the copy sheets through the optical path of various types of light image projection equipment.
Yet a further object is to control the instant in time that a copy sheet is permitted to move into the optical path of copying equipment so that a transferred toned image is substantially intact.
In a similar vein, it is an object of the invention to move the copy sheets in a copying machine in a manner that permits a rapid and non-interferring intersection of the machine's optical path.
Specifically, in a copying machine of the type wherein a linear image segment of a document is created by moving a scanning device relative to a stationary platen, it is an object to move a copy sheet through the optical path associated with the scanning device by allowing the copy sheet to move with the scanning device but at a position to not interfere with the formation of copies.
Also, in copying machines having flash illumination systems for creating light images for projection to a planer photoresponsive medium, it is an object to move a copy sheet through the optical path associated with the illumination system at times outside the flash intervals.
Yet a further object, in copying machines of the type wherein the platen or document moves relative to a stationary lens system, is to move a copy sheet through the effective optical path of the lens system without interferring with the creation of a copy.
Still a further object of the instant invention is the synchronization of copy sheet movement within a copying machine with the machine operations giving rise to the creation of a copy such that the copy sheet can intersect the optical path of the machine without impairing the resultant copy.
Clearly, a major object of the present inventive effort is to enhance the compactness of copying machines.